US2211145A - Picture transmitter - Google Patents

Picture transmitter Download PDF

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Publication number
US2211145A
US2211145A US10121336A US2211145A US 2211145 A US2211145 A US 2211145A US 10121336 A US10121336 A US 10121336A US 2211145 A US2211145 A US 2211145A
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US
United States
Prior art keywords
screen
potential
collecting electrode
lag
scanning
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
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English (en)
Inventor
Miller Harold
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
EMI Ltd
Electrical and Musical Industries Ltd
Original Assignee
EMI Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by EMI Ltd filed Critical EMI Ltd
Application granted granted Critical
Publication of US2211145A publication Critical patent/US2211145A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/26—Image pick-up tubes having an input of visible light and electric output
    • H01J31/28—Image pick-up tubes having an input of visible light and electric output with electron ray scanning the image screen
    • H01J31/30—Image pick-up tubes having an input of visible light and electric output with electron ray scanning the image screen having regulation of screen potential at anode potential, e.g. iconoscope
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
    • H01J29/36—Photoelectric screens; Charge-storage screens
    • H01J29/39—Charge-storage screens
    • H01J29/45—Charge-storage screens exhibiting internal electric effects caused by electromagnetic radiation, e.g. photoconductive screen, photodielectric screen, photovoltaic screen
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/26—Image pick-up tubes having an input of visible light and electric output
    • H01J31/28—Image pick-up tubes having an input of visible light and electric output with electron ray scanning the image screen
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/31678—Of metal

Definitions

  • the present invention relates to cathode ray.
  • efiect is exhibit-,- ed by water-free crystalline materials, either in the form of single crystals or of compressed polycrystalline powders, having a high refractive index, greater than 2, and include i (a) sulphides of many heavy metals such as copper, lead, thallium, mercury, cadmium, silver, zinc and antimony;
  • a cathode ray transmitting tube- is employed in a ,television transmitting system.
  • such tube comprising a conductive screen coated with a ma-- terial exihibiting a photo-conductive" eflect,
  • a cathode ray gun for developing a cathode beam, means for causing the conductive materialthe striking velocity is prefthe thickness of thecoating of the photo-conto scan the screen and an electrode for collecting secondary electrons liberated'irom the screen and wherein a potential difference is applied between the screen and the. collecting electrode not exceeding 100 volts.
  • Various materials may" be employed for coating the screen-and of such materials which will be hereinafter more particu-- larly referred to, zinc selenideis preferred and when employing such material the potential difference between the screen and the collecting 10 electrode should not exceed 50 "volts but should preferably be-in the region of'5-1-0'volts.
  • lag can be entirely eliminated by maintaining the screen and the collecting electrode at the same potential such as for example, at earth potential.
  • a further feature'of the invention consists in adjusting the striking velocity of the scanning electrons to a value of about 1-4 kilovolt's and u when zinc selenide is employed as the photoerablyin the region of l kilovolt.
  • ductlve material is small compared with the diameter of the scanning spot.
  • a collecting electrode 3 which serves to collect slstent with satisfactory sensitivity but such a 1i: 7 decrease in the potential difference between the secondary electrons liberated from the screen when the latter is scanned by a cathode ray beam generated in known manner from a cathode ray.
  • gun 5 indicated, diagrammatically, the beam being focussed by one or more focussing electrodes not shown in known manner.
  • 'I'he'cathode ray beam is caused to scan the image projected on the screen I by suitable means indicated at i and comprising coils which generate suitable magnetic. fields, or comprising :plates between which electrostatic fields are formed for the same purpose. The arrangement so far described is similar.
  • the screen I is connected through a resistance I and a source of potential 8 to earth and through a condenser 9 to the control grid of an amplifying valve I0. which is provided in the usual way with a leak II to earth. Since the source of potential 0 is connected between the screen I and earth, and the collecting electrode 3 is connected to earth, the potential source 8 will maintain a uniform diflerence of potential material, after suitable grinding is deposited upon.
  • a metal backing is 'formed by coating an insulating sheet such as mica with a metallic layer such as platinum deposited by a cathode sputtering process.
  • a metallic layer such as platinum deposited by a cathode sputtering process.
  • liquid silver a suspension of colloids; gold and colloidal palladium in a vapourisable medium such as tile.
  • the sensitive material may be deposited by spraying, sublimation, settling from suspension or by chemical action between suitable substances spread upon the backing surface.
  • the method chosen will depend upon the nature of the material used. It is important that the coating should be uniform and this has been found diflicult of achievement (at least in the case of zinc sulphide and selenide) with the spraying method, and hence the preferred method in the case of these two substances is to deposit the material by settling from a suspension in a liquid.
  • the side of the screen bearing the sensitive material or the backing may be transparent and the optical image may be cast on the sensitivematerial through the backing.
  • the optical axis of the image projector and the mean direction of the scanning beam may be both normal to the screen.
  • the screen When the screen is prepared by settling from I suspension it is preferred to allow the material to settle on to a metal disc instead of on to a metallized piece of mica, although the metal disc trode 3, insufllcient current in the scanning beam thereof.
  • the optical image may be cast upon and the use of unsuitable striking velocities in the scanning electrons.
  • the striking velocity of the beam is dependent upon the potential difference between the screen I and the cathode ray gun II. It is found that over the lower range of positive values of the potential difference between the screen I and the collecting electrode 3, that is to say, those values in which the collecting electrode is positive with respect to the screen.
  • the sensitivity increases with an increase in such 1 potential difference.
  • the collecting electrode 3 is at a positive potential with respect to the screen I to which is applied a negative potential from battery I and at a predetermined value a positive pulse is generated when the screen is scanned, butjby arranging the electrode 3 to be at a negative potential with respect to the screen I.a response in the opposite direction can be generated.
  • lag can be made substantially zero by maintaining the electrode 8 and the screen I at substantially the same potential.
  • the screen I can be maintained at earth potential corresponding to the potential of the electrode 3.
  • the tilting effect can be reduced to substantiallyzero by maintaining a large potential difference between the screen I and the collecting electrode 3.
  • Such a method of operation results in the introduction of'a degree of lag which would be intolerable for the transmission of the images of moving objects, but which may satisfactorily be employed for the transmission of "still images.
  • the lag has been found to decrease with increase in the striking velocity of the scanning beam, such striking velocity, as aforesaid being determined by the potential diilerence between the electron gun and the screen I.
  • the thickness of the layer of the zinc selenide applied tothe screen I also to some extent determines the required striking velocity and with a layer having a thickness of the order of one to three times cms. the striking velocity is found to be about 1-2 kilovolts.
  • the diameter of the scanning spot be larger than the thickness of the coating, and in a case in which scanning is accomplished in 400 lines, the diameter of the scanning spot may be of the order of two to three times 10- cms; and in such case it will be observed that the coating thickness abovementioned is small compared with this spot diameter.
  • a cathode ray tube having a conductive signal plate having on its surface a non-photo-emissive layer of photo-conductive material comprising zinc selenide, said tube having included therein a source for producing a concentrated electron scanning beam and an electron collecting electrode located intermediate the signal plate and the electron source and an output impedance con- I ductively connected to the signal plate, the
  • method of television which comprises projecting an optical image upon the photo-conductive layer of the signal plateto vary its photo-conductivity in proportion to the intensity of the optical image and thereby producing an electrical counterpart being less than 50 volts whereby an optimum ratio of sensitivity of the photo-conductive layer to the lag effectis obtained, then traversing the area ofthe signal plate by the concentrated elec-- tron scanning beam to scan the electrical counterpart of the optical image as developed on the-signal plate and thereby releasing from the signal plate to the collecting electrode secondary electrons in substantial'proportion to the light of the optical image at the area scanned and then deriving from the output impedance a signal voltage representing the scanned optical image.
  • a cathode ray tube having a conductive signal plate having on its surface a non-photo-emissive layer the signal plate and the electronsource and an output impedance conductively connected to the signal plate
  • the method of television which comprises projecting an optical image upon thephoto-conductive layer of the signal plate to vary its photo-conductivity in proportion to the intensity of the optical image and thereby producing an electrical counterpart of the optical image, establishing a substantially uniform normal potential difference between substantially the entire area of the signal plate and the collecting electrode, said potential dif Schlpe being less than 50 volts whereby an optimum ratio of sensitivity of the photo-conductive layer to the lag efiect is obtained; focusing the concentrated electron scanning beam at its point of impact on the photoconductive signal plate so that its diameter is greater than the thickness of the said photo-conductive layer, then traversing the area of the signal plate by the concentrated electron scanning beam to scan the electrical counterpart of the optical image as developed on the signal plate and thereby releasing from the signal plate to the collecting electrode secondary

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
  • Photoreceptors In Electrophotography (AREA)
US10121336 1935-09-24 1936-09-17 Picture transmitter Expired - Lifetime US2211145A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB2188336A GB463297A (en) 1935-09-24 1935-09-24 Improvements in or relating to cathode ray tube television transmitting apparatus
GB2989235A GB465060A (en) 1935-09-24 1935-10-29 Improvements in and relating to cathode ray tube television transmitting apparatus

Publications (1)

Publication Number Publication Date
US2211145A true US2211145A (en) 1940-08-13

Family

ID=32071294

Family Applications (3)

Application Number Title Priority Date Filing Date
US10121336 Expired - Lifetime US2211145A (en) 1935-09-24 1936-09-17 Picture transmitter
US10206836 Expired - Lifetime US2211146A (en) 1935-09-24 1936-09-23 Picture transmitter
US10548036 Expired - Lifetime US2177736A (en) 1935-09-24 1936-10-14 Television transmitting apparatus

Family Applications After (2)

Application Number Title Priority Date Filing Date
US10206836 Expired - Lifetime US2211146A (en) 1935-09-24 1936-09-23 Picture transmitter
US10548036 Expired - Lifetime US2177736A (en) 1935-09-24 1936-10-14 Television transmitting apparatus

Country Status (5)

Country Link
US (3) US2211145A (enrdf_load_stackoverflow)
DE (1) DE897850C (enrdf_load_stackoverflow)
FR (1) FR811932A (enrdf_load_stackoverflow)
GB (2) GB463297A (enrdf_load_stackoverflow)
NL (1) NL45505C (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2888370A (en) * 1957-02-26 1959-05-26 Gen Electric Photoconductor of lead oxide and method of making
US2890359A (en) * 1953-06-13 1959-06-09 Philips Corp Camera tube
US2924655A (en) * 1956-02-18 1960-02-09 Philips Corp Device comprising a cathode-ray tube for producing a signal delay
US3321656A (en) * 1954-03-11 1967-05-23 Edward E Sheldon Television camera tube with lead oxide screen

Families Citing this family (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3123737A (en) * 1964-03-03 schneeberger
US3127333A (en) * 1964-03-31 bonrud
US2899488A (en) * 1959-08-11 Nesa strips
US2422970A (en) * 1942-09-24 1947-06-24 Gen Electric Photoelectric discharge device
BE488137A (enrdf_load_stackoverflow) * 1948-03-29
US2699512A (en) * 1951-11-21 1955-01-11 Sheldon Edward Emanuel Camera for invisible radiation images
US2768318A (en) * 1952-10-03 1956-10-23 Philco Corp Screen structure for cathode ray tubes
NL92219C (enrdf_load_stackoverflow) * 1953-08-04
GB784863A (en) * 1954-07-27 1957-10-16 Emi Ltd Improvements in or relating to electron discharge devices employing photo-conductivetargets
US2911561A (en) * 1954-08-11 1959-11-03 Thompson Ramo Wooldridge Inc Automatic target current control circuit
US3015746A (en) * 1955-02-15 1962-01-02 Emi Ltd Electron discharge devices employing photo-conductive target electrodes
US2939027A (en) * 1955-10-06 1960-05-31 Gen Electric Photoconductive image transducer tubes
US3008825A (en) * 1957-11-20 1961-11-14 Xerox Corp Xerographic light-sensitive member and process therefor
US3950272A (en) * 1974-01-30 1976-04-13 Shmuel Mardix Method of preparing conductron-type photoconductors and their use as target materials for camera tubes

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2890359A (en) * 1953-06-13 1959-06-09 Philips Corp Camera tube
US3321656A (en) * 1954-03-11 1967-05-23 Edward E Sheldon Television camera tube with lead oxide screen
US2924655A (en) * 1956-02-18 1960-02-09 Philips Corp Device comprising a cathode-ray tube for producing a signal delay
US2888370A (en) * 1957-02-26 1959-05-26 Gen Electric Photoconductor of lead oxide and method of making

Also Published As

Publication number Publication date
FR811932A (fr) 1937-04-26
DE897850C (de) 1953-11-26
US2177736A (en) 1939-10-31
NL45505C (enrdf_load_stackoverflow) 1900-01-01
GB463297A (en) 1937-03-24
US2211146A (en) 1940-08-13
GB465060A (en) 1937-04-29

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